Natural gas

Natural gas is a gas produced by the anaerobic decay of organic material. It is usually found in oil fields and natural gas fields, but is also generated in swamps and marshes (where it is called swamp gas or marsh gas), in landfill sites, and during digestion in animals (see flatulence).

Chemical composition and energy content

Chemical composition

The primary component of natural gas is methane (CH₄), the shortest and lightest hydrocarbon molecule. It may also contain heavier gaseous hydrocarbons such as ethane (C₂H₆), propane (C₃H₈) and butane (C₄H₁₀), as well as other gases, in varying amounts. Hydrogen sulfide (H₂S) and mercury (Hg) are common contaminants, which must be removed prior to most uses.

Energy content

Combustion of one hundred cubic feet (1 ccf) of commercial quality natural gas typically yields approximately 1 therm (100,000 british thermal units, 30 kWh). One cubic meter yields 38 MJ (10.6 kWh).

Storage and transport

The major difficulty in the use of natural gas is transportation. Natural gas pipelines are economical, but are impractical across oceans. Many existing pipelines in North America are close to reaching their capacity prompting some politicians in colder climates to speak publicly of potential shortages. Liquefied natural gas (LNG) tankers are also used, but have higher cost and safety problems. In many cases, as with oil fields in Saudi Arabia, the natural gas which is recovered in the course of recovering petroleum cannot be profitably sold, and is simply burned at the oil field (known as flaring). This wasteful practice is now illegal in many countries, especially since it adds greenhouse gas pollution to the atmosphere, and since a profitable method may be found in the future. The gas is instead re-injected back into the ground for possible later recovery, and to assist oil pumping by keeping underground pressures higher.

Natural gas is often stored as Compressed Natural Gas or CNG.

Future use as a fuel

Many politicians and prominent figures in North America have spoken publicly about the looming natural gas crisis. This list includes Secretary of Energy Spencer Abraham, Chairman of the Federal Reserve Alan Greenspan, Ontario Minister of Energy Dwight Duncan.

It is unclear if the problem will be one of supply or transporting the gas to the end users from the known reserves.

Uses

Power generation

Natural gas is important as a major source for electricity generation through the use of gas turbines and steam turbines. Environmentally, natural gas burns cleaner than other fossil fuels, although it does produce greenhouse gases and is ultimately unsustainable. Its extraction and transportation can generate additional pollution.

Natural gas vehicles

Compressed Natural Gas (and LPG) is used as a clean alternative to other automobile fuels. As of 2003, the countries with the largest number of natural gas vehicles were Argentina, Brazil, Pakistan, Italy, and India.

Domestic use

Natural gas is supplied to homes where it is used for such purposes as cooking and heating. CNG is used in rural homes without connections to piped-in public utility services, or with portable grills.

Sources

Natural gas is commercially produced from oil fields and natural gas fields

Possible future sources

One experimental idea is to use the methane gas that is naturally produced from landfills to supply power to cities. Tests have shown that methane gas could be a financially sustainable power source.

There are plans in Ontario to capture the methane gassses rising from the manure of cattle caged in a factory farm and to use that gas to provide power (2500 MW) to a small town.

There is also the possibility that with source seperation of organic materials from the waste stream that by using an anerobic digester , the methane can be used to produce useable energy.

Safety

In any form, a strong bad scent (such as ethyl mercaptan) is deliberately added to the otherwise colorless and odorless gas, so that leaks can be detected by the smell before an explosion occurs. In mines, sensors are used and mining apparatus has been specifically developed to avoid ignition sources (e.g. the Davy lamp)

Natural gas is non-toxic, though some gas fields yield 'acid gas' containing hydrogen sulfide. This untreated gas is toxic.

External links

Natural gas vehicles

• International Natural Gas Vehicle Statistics (http://www.iangv.org/jaytech/default.php?PageID=130)

North America

• What is Compressed Natural Gas? (http://www.energyquest.ca.gov/transportation/CNG.html)
• Could CNG work in America? (http://www.wokr13.tv/news/local/story.aspx?content_id=B841A1FA-0DAA-4EA3-88E5-EFB409DF3F38)

South Asia

• Pakistan: Conversion to CNG up 64% from last year (http://www.dailytimes.com.pk/default.asp?page=story_18-1-2004_pg5_4)
• Pakistan: Daily Times stories about cheap ($2000 - $3000) CNG cars: [1] (http://www.dailytimes.com.pk/default.asp?page=story_27-12-2003_pg5_9) [2] (http://www.dailytimes.com.pk/default.asp?page=story_20-3-2004_pg5_5)
• India: How New Delhi used CNG to ease pollution (http://cities.expressindia.com/fullstory.php?newsid=85665)

ca:Gas natural cy:Nwy naturol de:Erdgas es:Gas natural fr:Gaz naturel he:גז_טבעי nl:Aardgas ja:天然ガス simple:Natural gas fi:Maakaasu zh:天然气